Lack of expression phosphotyrosinephosphatase SHP-1 in K562 cells results from hypermethylation of the SHP-1 promoter
| Autor: | Lin-Ya Tang, 唐鈴雅 |
|---|---|
| Rok vydání: | 2002 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 90 Chronic myelogenous leukemia (CML) is a hematological stem cell disorder. It is the first human malignancy shown to be associated with a specific Philadelphia (Ph1) translocation. The product of this translocation, Bcr-Abl protein, is considered to play a crucial role in the pathogenesis of CML. The progress of CML can be classified into three stages: chronic phase, accelerated phase, and blast crisis phase. The patients in chronic phase respond very well to chemotherapy and other treatments, while the treatment in acute phase was almost failed. Therefore, it is important to diagnose the disease in chronic phase. The Ph chromosome presents in about 90% of CML patients and also a good diagnostic tool for the diagnosis CML. We used the nested RT-PCR to detect Bcr-Abl fusion gene. The technique has a high sensitivity for detection of CML patients (17/20). However, we found that some normal individuals also express Bcr-Abl mRNA (1/51). We speculated that other factor(s) regulated the Bcr-Abl protein activity, and then the CML model cell line, K562, was used to study the expression of Bcr-Abl related proteins. We found that the K562 cells failed to express SHP-1 gene. After K562 cells were treated with 4mM of 5-Aza-2’-deoxycytidine or 1.5mM of sodium butyrate for four days, the cells re-expressed the SHP-1 mRNA when detected by RT-PCR. This suggests that SHP-1 gene expression is regulated by DNA methylation. To analyze DNA methylation sites, we used either methylation-sensitive HpaII to digest DNA or sodium bisulfite to modify DNA. The modified DNA was subjected to DNA sequencing, and the results showed that at least nine CpG islands in SHP-1 promoter region were methylated. Using these data we could search for the binding element of transcription factors in the SHP-1 promoter and study the role of SHP-1 in the CML progress. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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